The main abrasive pressure in the Icelandic Waters ecoregion is caused by mobile bottom-fishing gears (targeting fish, shrimp, and Norway lobster Nephrops norvegicus). Other occasional abrasion pressures (surface and subsurface) that exert localized impacts include telecommunication and power cable laying on the ocean floor, anchoring, and static gears.
Based on analysis of electronic logbook data an area of about 79 000 km2 in total was fished with towed bottom-fishing gears in 2013, composing 10% of the ecoregion. The total fishing effort by bottom trawls targeting fish and shrimp has decreased by around 40% in 2000–2014; in the same period the Nephrops trawling effort remained at the same level. The decrease in fishing effort varied locally, with decreases mainly being noted on the southern shelf (Subarea 1) and at typical shrimp trawling grounds on the northern shelf (figure 7 and figure 8).
Within the ecoregion, abrasion caused by bottom trawls has been shown to impact fragile three-dimensional biogenic habitats in particular (e.g. sponge aggregations, coral gardens, and coral reefs), with impacts happening mainly in deeper waters ( > 200 m). Effects of bottom trawling on soft substrates in shallow waters have been shown to be minor. Other impacts involve overturning boulders, scouring the seabed, and direct removal of and/or damage to epifaunal organisms.
Figure 7: Annual total bottom-trawl fishing effort (1000 kW day) based on logbooks from trawl fishery targeting (a) fish, (b) Norway lobster, and (c) shrimp in the whole Icelandic Waters ecoregion between 1994 and 2014.
Figure 8: Spatial
distribution of bottom-trawl effort (1000 kW hr) based on logbooks
from trawl fishery targeting demersal fish, shrimp, and Norway lobster in 2000,
2005, 2010, and 2014.